Reciprocating-piston internal combustion (IC) engines are known for converting chemical energy from a fuel supply into mechanical shaft power. A fuel-oxidizer mixture is received in a variable volume of an IC engine defined by a piston translating within a cylinder bore. The fuel-oxidizer mixture burns inside the variable volume to convert chemical energy from the mixture into heat. In turn, expansion of the combustion products within the variable volume performs work on the piston, which may be transferred to an output shaft of the IC engine.
Some constituents in the exhaust stream from an IC engine, such as, for example, nitrogen oxides (NOx), unburned hydrocarbons (UHCs), and particulate matter (PM), may be subject to government regulations. Accordingly, operators may wish to control concentrations of regulated exhaust constituents released to the environment. The composition of exhaust discharged from an IC engine may be affected by control of the combustion process within the variable volume combustion chamber, exhaust aftertreatment downstream of the combustion chamber, or combinations thereof.
Some IC engines employ an externally-powered ignition source to initiate combustion of the fuel-oxidizer mixture within the variable volume. For example, an IC engine may include a spark plug defining a spark gap between an anode and a cathode, where the spark gap is in fluid communication with the variable volume and in electrical communication with an electric potential. Accordingly, applying the electric potential across the spark gap may cause an electric spark to arc across the spark gap, thereby initiating combustion of the fuel-oxidizer mixture within the variable volume.
U.S. Pat. No. 8,215,284 (hereinafter “the '284 patent”), entitled “Micro-Pilot Injection Ignition Type Gas Engine,” purports to address the problem of starting a dual gaseous and liquid fueled engine. The '284 patent describes a micro-pilot injection ignition type gas engine and an air-fuel ratio control method thereof. According to the '284 patent gaseous fuel and air are mixed upstream of an intake valve, and the mixture of air and gaseous fuel are admitted into a combustion chamber during an intake stroke, while the intake valve is open. During a subsequent compression stroke, a portion of the mixture of air and gaseous fuel flow into a pre-chamber via at least one pre-chamber nozzle hole.
Next according to the '284 patent, a fuel oil injector injects a small amount of fuel oil into the pre-chamber, and a mixture of the fuel oil injection and air autoignites within the pre-chamber. Autoignition of the fuel oil-air mixture within the pre-chamber further ignites the mixture of air and gaseous fuel within the pre-chamber, thereby causing hot combustion products within the pre-chamber to jet out through the at least one pre-chamber nozzle hole into the combustion chamber. In turn, the jets of combustion products from the pre-chamber ignite the mixture of air and gaseous fuel within the combustion chamber.
However, the ignition strategy described in the '284 patent requires that two different types of fuel, namely a gaseous fuel and a liquid fuel oil, be available to the engine, which may cause logistical challenges in providing two different fuel types to the engine, as well as operational challenges in balancing consumption of the two different fuel types as not to prematurely deplete one of the two fuel types. Accordingly, there is a need for improved gaseous fuel combustion systems for internal combustion engines to address the aforementioned challenges and/or other problems in the art.
It will be appreciated that this background description has been created to aid the reader, and is not a concession that any of the indicated problems were themselves known previously in the art.